This application claims the priority of Korean Patent Application No. 2003-100495, filed on Dec. 30, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to an ion implanter used for manufacturing a semiconductor device, and more particularly, to a manipulator assembly in an ion implanter.
2. Description of the Related Art
An ion implanter is used to dope semiconductor wafers with impurities in the manufacture of a semiconductor device. The ion implanter includes an ion source portion which produces ion beams with which the semiconductor wafer is to be doped, and a manipulator assembly which focuses the ion beams. The ion beams pass through the manipulator assembly, undergo various filtering processes, and are implanted into the semiconductor wafer.
FIG. 1 is a schematic view for illustrating an ion source portion, and a manipulator assembly in an ion implanter, according to the prior art, and FIG. 2 is a perspective view of the manipulator assembly in the ion implanter of FIG. 1.
Referring to FIGS. 1 and 2, the ion implanter includes an ion source portion 100 which produces ion beams IB, and a manipulator assembly 200 which is adjacent to the ion source portion 100, and focuses the ion beams IB.
The ion source portion 100 includes an arc chamber 102 which arc-discharges a supplied source gas to produce the ion beams IB. The ion beams IB are discharged through a first hole 104 which is provided on a side of the arc chamber 102.
The manipulator assembly 200 includes a ground electrode 202. First and second suppression electrodes 204 and 206 are positioned at predetermined distances from the left and right sides of the ground electrode 202, respectively. The first and second suppression electrodes 204 and 206 are electrically interconnected and supported by connection legs 208. The first suppression electrode 204 keeps a distance L1 from the ground electrode 202, and the second suppression electrode 206 keeps a distance L2 from the ground electrode 202. The distance L2 is longer than the distance L1.
Insulators 210 are positioned between the first suppression electrode 204 and the ground electrode 202. A voltage difference between the first and second suppression electrodes 204 and 206 and the ground electrode 202 is kept at about 5 kV during implantation of the ion beams IB. A ground shield 212 is attached to a side of the ground electrode 202 so that the ion beams IB are not adhered onto the ground electrode 202.
The ion beams IB are supplied to a second hole 214 made in the first suppression electrode 204 of the manipulator assembly 200 via the first hole 104 of the arc chamber 102. The ion beams IB are controlled, focused, and discharged via a third hole 216 made in the ground electrode 202 and a fourth hole 218 made in the ground shield 212.
FIG. 3 is a graph for showing variations in a suppression current with respect to the time required for using the ion implanter of FIGS. 1 and 2.
As described above, the manipulator assembly 200 in the ion implanter of FIGS. 1 and 2 insulates the first suppression electrode 204 from the second suppression electrode 206 using the insulators 210. Also, the voltage difference between the first suppression electrode 204 and the ground electrode 202 is kept at about 5 kV. However, as impurities are implanted into a plurality of portions of a semiconductor wafer using the ion implanter, i.e., the ion implanter is used for a long period of time, the ion beams IB are deposited on the insulators 210. This leads to a reduction in a resistance of the insulators 210, which results in increasing the suppression current as marked with ⋄. Thus, the manipulator assembly 200 must be periodically overhauled to overcome this problem.